The present invention relates to the use of Schülpen of pyrogenic silicic acid in pharmaceutical compositions. The Schülpen are used in this connection in particular as glidants to improve the bulk flow of powders.
In a medicament it is generally possible to distinguish two functionally different substance groups, namely active ingredients and auxiliary substances.
Active ingredients are characterised by their specific pharmacological activity. They represent the active constituent of a medicament. As such, they are also identified quantitatively on the packaging and on the package leaflet.
Auxiliary substances, on the other hand, have no pharmacological activity. They are necessary in order to enable a suitable form of administration, namely the medicament, to be produced for the active ingredient. In general, the medicament contains a plurality of auxiliary substances having different functions. For example, auxiliary substances are used as fillers, binders, disintegrators, glidants, lubricants or release agents.
When developing stable, effective medicaments which are easy to handle from active ingredient(s) and auxiliary substances, there are a large number of auxiliary substances which can be used.
Highly disperse, pyrogenic silicon dioxide, for example Aerosil®, is frequently used in pharmaceutical and cosmetic compositions. In solid product forms it can be used as a flow regulator, adsorbent and drying agent; in liquid and semi-liquid product forms it can be used as a suspension stabiliser, framework-forming agent and gel-forming agent. It can also be used to increase the mechanical stability and the rate of disintegration of tablets. In addition, it can improve the distribution of the active ingredient.
A particular disadvantage when working with highly disperse silicon dioxide is the formation of dust, because very high demands have to be met in terms of cleanliness when producing pharmaceutical and cosmetic products.
A further disadvantage is the agglomeration behaviour of highly disperse silicon dioxide, which causes the product to come together as a result of hydrogen bridges and electrostatic charging. This results in larger lumps which do not pass through the relatively small sieve openings typical for the pharmaceutical industry. This is a particular problem in the case of silicon dioxides which have been compressed in order to minimise dust formation and have a higher bulk and tamped density.
Sieving is very important in order to eliminate foreign bodies in pharmaceutical products. As a result, modern automatic weighing and screening devices cannot be used, which increases the possibility of contamination from human handling.
When using highly dispersed silicon dioxide in pharmaceutical compositions improved flowability of mixtures prepared therewith would also be desirable in order to be able to achieve greater metering accuracy, for example when producing tablets and capsules. As a result it would be possible on the one hand to achieve lower variance of tablet and capsule weights and on the other hand to improve the economy of processes that result in such forms of administration.